The invention relates to a method of estimating motion in an image by means of a motion estimator whose input receives a signal which supplies information about the pixels of the image, said image being represented by digital data comprising a luminance signal and a chrominance signal.
The invention also relates to a device provided with a motion estimator whose input receives a signal which supplies information about the pixels of an image for estimating motion in this image which is represented by digital data comprising a luminance signal and a chrominance signal.
Such a method and a device are used for reducing the digital data rate in digital television or in television using associated digital data ("DATV").
It is known to obtain motion information for elements of a television image by using a motion estimator, based on the luminance signal, which supplies a vector motion for the luminance. However, when the luminance is constant when the chrominance signal level varies (for example, when moving the camera along banners against a uniform sky, with the luminance of the banner and that of the sky being equal or substantially equal, billboards, etc.) the motion estimator will operate erroneously, which becomes manifest in a disturbing phenomenon in the reproduced image. An evident solution would be to use a second motion estimator, based on the chrominance signal, supplying a vector motion for the chrominance, and to transmit the value of the chrominance vector motion, or to weight the luminance vector by the chrominance vector.
These options have the drawback that they are difficult to realise in hardware, while they also involve a modification of the data transmission standard.
It is, inter alia, an object of the invention to provide a solution for these drawbacks.